19-2613; Rev 0; 10/02 MAX1858 Evaluation Kit Features ♦ 8V to 20V Input Voltage Range ♦ 1.8V and 2.5V Adjustable Output Voltages ♦ 10A Output Current (2.5V Output) ♦ 10A Output Current (1.8V Output) ♦ Lossless Foldback Current Limit ♦ 600kHz Switching Frequency ♦ RST Output with 140ms Delay ♦ 180 Degrees Out-of-Phase Operation ♦ 24-Pin QSOP Package ♦ Low-Profile Components ♦ Fully Assembled and Tested Ordering Information PART MAX1858EVKIT TEMP RANGE 0°C to +70°C IC PACKAGE 24 QSOP Component List DESIGNATION QTY C1–C4 4 C5, C6, C22 3 DESCRIPTION 10µF, 25V ceramic capacitors (1812) Taiyo Yuden TMK432BJ106KM or TDK C4532X5R1E106M 0.1µF ceramic capacitors (0805) C7 1 0.01µF ceramic capacitor (0805) C8 1 C9–C16 8 0.0068µF ceramic capacitor (0805) 220µF, 4V, 40mΩ low-ESR capacitors Sanyo 4TPC220M 100pF ceramic capacitors (0805) C17, C18 C19 C20 C21 D1 D2, D3 D4, D5 2 1 1 1 1 2 2 0.22µF, 16V X5R ceramic capacitor (0805) Taiyo Yuden EMK212BJ224KG or TDK2012X7R1H224KT 4.7µF, 10V X5R ceramic capacitor (1206) Taiyo Yuden LMK316BJ475ML 0.22µF, 50V X7R ceramic capacitor (0805) Taiyo Yuden UMK212BJ224MG or TDK C2012X7R1H224M 100mA, 30V dual Schottky diode Central Semiconductor CMPSH-3A 3A, 30V Schottky diodes Nihon EC31QS03L 100mA, 30V Schottky diodes Central Semiconductor CMSSH-3 DESIGNATION JU1, JU2 L1, L2 N1–N4 R1 QTY DESCRIPTION 2 3-pin headers 1.1µH power inductors 2 Sumida CEP12D38-H-1R1 (18.1A, 6mΩ, 12.5mm x 12.5mm x 4.0mm) N-channel MOSFETs 8-pin SO 4 International Rectifier IRF7811W or Fairchild FDS6694 1 8.06kΩ ±1% resistor (0805) R2, R4, R5 3 10kΩ ±1% resistors (0805) R3 1 15kΩ ±1% resistor (0805) R6 1 8.2kΩ ±5% resistor (0805) R7 1 5.9kΩ ±5% resistor (0805) R8 1 97.6kΩ ±1% resistor (0805) R9 1 140kΩ ±1% resistor (0805) R10 1 100kΩ ±5% resistor (0805) R11 1 4.7Ω ±5% resistor (0805) R12, R13 2 4.7Ω ±5% resistors (0603) R14 1 118kΩ ±1% resistor (0805) R15 1 84.5kΩ ±1% resistor (0805) None 2 Shunts U1 1 MAX1858EEG 24-pin QSOP None 1 MAX1858 PC board ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 Evaluates: MAX1858/MAX1875/MAX1876 General Description The MAX1858 evaluation kit (EV kit) demonstrates the MAX1858’s standard application circuit. This dual PWM synchronous DC-to-DC converter generates outputs down to 0.75V for core, I/O, and logic supplies. The MAX1858 EV kit provides dual 1.8V and 2.5V output voltages from an 8V to 20V input voltage range. It delivers up to 10A output current for the 2.5V output and 10A for the 1.8V output with greater than 90% efficiency. Both converters operate 180 degrees out-of-phase to reduce input ripple current. The EV kit operates at 600kHz switching frequency and has superior line- and loadtransient response. This EV kit is a fully assembled and tested circuit board. It allows evaluation of other output voltages in the 0.75V to 15V range. The MAX1858 EV kit can also be used to evaluate the MAX1875 and MAX1876. Evaluates: MAX1858/MAX1875/MAX1876 MAX1858 Evaluation Kit Component Suppliers SUPPLIER PHONE FAX WEBSITE Central Semiconductor 516-435-1110 516-435-1824 Fairchild 408-721-2181 408-721-1635 www.centralsemi.com www.fairchildsemi.com International Rectifier 310-322-3331 310-322-3332 www.irf.com Nihon 847-843-7500 847-843-2798 www.niec.co.jp Sanyo 619-661-6835 619-661-1055 www.sanyovideo.com Sumida 708-956-0666 708-956-0702 www.sumida.com Taiyo Yuden 408-573-4150 408-573-4159 www.t-yuden.com TDK 847-390-4373 847-390-4428 www.component.tdk.com Note: Please indicate that you are using the MAX1858 when contacting these component suppliers. _________________________Quick Start The following equipment is required before beginning: • 8V to 20V power supply • Electronic loads capable of sinking 10A each • Digital multimeters (DMMs) • 100MHz dual-trace oscilloscope Follow these steps to verify board operation. Do not turn on the power supply until all connections are completed: 1) Ensure that the circuit is connected correctly to the supply and electronic loads before applying any power. Set the electronic loads in resistive mode. 2) Verify that the shunts are across JU1 pins 1 and 2 and JU2 pins 1 and 2. Evaluating Other Output Voltages The EV kit outputs are programmed for 1.8V and 2.5V. However, the output voltages can also be adjusted between 1V and 15V by selecting R1/R2 and R3/R4 values. Select feedback resistors R2 and R4. R1 and R3 are then given by: R1 (or R3) = R2 (or R4) x [(VOUT / VFB) - 1] where VFB = 1V. Refer to the MAX1858 data sheet for selection of output capacitors, inductors, and compensation networks. For output voltages below 1V, refer to Figure 6 in the MAX1858 data sheet. Evaluating MAX1875/MAX1876 Replace U1 with the MAX1875/MAX1876. 3) Turn on power supply. 4) Verify that the output voltages are 1.8V and 2.5V. Table 1. JU1 Functions (EN Mode Selection) JU1 EN PIN 1 and 2 Connected to VL 2 and 3 Connected to GND Not Installed 2 Connected to EN pad Table 2. JU2 Functions (SYNC Mode Selection) JU2 SYNC PIN MAX1858 enabled, VOUT1 = 1.8V and VOUT2 = 2.5V 1 and 2 Connected to VL Shutdown mode, VOUT1 = 0V and VOUT2 = 0V 2 and 3 Connected to GND Used to sync up an additional single buck. CKO is the same frequency and phase as DH1. Not Installed Connected to SYNC pad External clock is applied to SYNC input (1100kHz to 1300kHz) MAX1858 OUTPUT MAX1858 must be enabled by an external signal EFFECT Used to sync up an additional MAX1858. CKO is 2x DH1 and phase shifted by 90 degrees. _______________________________________________________________________________________ _______________________________________________________________________________________ VOUT1 1.8V CKO SYNC EN RST R10 100kΩ VL C11 C12 C9 C10 220µF 220µF 220µF 220µF 4V 4V 4V 4V GND C1 10µF 25V R2 10kΩ 1% 7 8 3 1 2 D2 3 N1 C7 0.01µF R1 8.06kΩ 1% L1 1.1µH C2 10µF 25V 7 8 1 JU2 VL 3 N3 2 6 5 4 D4 1 4 R7 5.9kΩ 2 6 5 3 1 2 C5 0.1µF BST1 R5 10kΩ 1% JU1 VL C17 100pF 4 8 9 24 13 12 11 18 7 17 R12 4.7Ω 15 16 14 5 V+ OSC CKO SYNC EN RST COMP1 FB1 PGND GND DL1 LXI BST1 DH1 C21 0.22µF 50V MAX1858 U1 L FB2 DL2 LX2 BST2 DH2 19 VL 3 ILIM2 ILIM1 REF COMP2 C22 0.1µF 1 2 3 10 6 1 2 20 BST2 VOUT2 C19 0.22µF C18 100pF R13 22 4.7Ω 21 23 VL D1 C20 4.7µF 10V R R8 97.6kΩ 1% R14 118kΩ 1% R6 8.2kΩ D5 3 87 4 C6 0.1µF BST2 VL 5V 4 5 2 1 R9 140kΩ 1% R15 84.5kΩ 1% R4 10kΩ 1% R3 15kΩ 1% L2 1.1µH C8 0.0068µF D3 21 N2 65 VOUT1 N4 6 3 87 C3 10µF 25V VIN C15 C16 C13 C14 220µF 220µF 220µF 220µF 4V 4V 4V 4V C4 10µF 25V VOUT2 2.5V Evaluates: MAX1858/MAX1875/MAX1876 VIN R11 4.7Ω BST1 MAX1858 Evaluation Kit Figure 1. MAX1858 EV Kit Schematic 3 Evaluates: MAX1858/MAX1875/MAX1876 MAX1858 Evaluation Kit Figure 2. MAX1858 EV Kit Component Placement Guide—Top Silkscreen 4 Figure 3. MAX1858 EV Kit PC Board Layout—Component Side _______________________________________________________________________________________ MAX1858 Evaluation Kit Evaluates: MAX1858/MAX1875/MAX1876 Figure 4. MAX1858 EV Kit PC Board Layout—Ground Layer 2 Figure 5. MAX1858 EV Kit PC Board Layout—Ground Layer 3 _______________________________________________________________________________________ 5 Evaluates: MAX1858 MAX1875/MAX1876 MAX1858 Evaluation Kit Figure 6. MAX1858 EV Kit PC Board Layout—Solder Side Figure 7. MAX1858 EV Kit Component Placement Guide— Bottom Silkscreen Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.